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Date: Thu, 14 Jun 2001 05:47:31 -0700 (PDT)
From: Thierry Herbelot <thierry@herbelot.com>
To: freebsd-gnats-submit@freebsd.org
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Subject: docs/28143: the Hz kernel config option is not documented
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>Number:         28143
>Category:       docs
>Synopsis:       the Hz kernel config option is not documented
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-doc
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          doc-bug
>Submitter-Id:   current-users
>Arrival-Date:   Thu Jun 14 05:50:01 PDT 2001
>Closed-Date:
>Last-Modified:
>Originator:     Thierry Herbelot
>Release:        FreeBSD 4.3-Release
>Organization:
>Environment:
FreeBSD pc-bsd60.XXX 4.3-RELEASE FreeBSD 4.3-RELEASE #11:
Tue Apr 24 19:14:23 CEST 2001     
herbelot@pc-bsd60.XXXX:/usr/obj/usr/src/sys/station  i386
>Description:
The Hz kernel config option is referenced in the ipfw(8) man page 
(typically 10ms, but it is a good practice to run kernels with 
``options HZ=1000'' to reduce the granularity to 1ms or less) but is
nowhere to be seen in the usual kernel config help file (aka LINT) or 
in a man page (and neither in the handbook).

I am using HZ=5000 in some (around 100) PCs here, with no ill effects. 
As this feature is a great win for xxBSD (for example for real-time 
systems), it should be documented.
>How-To-Repeat:

>Fix:
Add a doc line in the LINT config file:
-----------------------------
options HZ=1000 # set the system clock to 1000 Hz 
                # (values above above 5000Hz should not be used)
-----------------------------
>Release-Note:
>Audit-Trail:
>Unformatted:

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